Formation sampler



Aug. 19, 1958 F. v. PORTER 2,848,195

FORMATION SAMPLER Filed Sept. 17, 1956 2 Sheets-Sheet 1 liIEg 4 IN V N To 0 225.57 4 p 7E2 F. v. PORTER FORMATION SAMPLER Aug. 19, 1958 Filed Sept. 17, 1956 2 Sheets-Sheet 2 IN V EN TOR. 02255 7 M POQEZ ;7C'7. 4. BY%

United States Patent FORMATION SAMPLER Forrest V. Porter, Monterey Park, Calif., assignor, by mesne assignments, to Dresser Industries, Inc., Dallas, Tex., a corporation of Delaware Application September 17, 1956, Serial No. 610,278

18 Claims. (Cl. 2551.4)

This invention relates to borehole sampler devices and, more particularly, to a so-called gun type sampler device employing sampling projectiles adapted to be projected into an earth formation by an explosive charge and thereafter retrieved along with a captive sample of the formation.

In the recovery of formation samples by the aid of hollow projectile type formation samplers as heretofore proposed, resort has been had to two different modes of stowing the retrieving cables connecting the sampling projectiles to the firing apparatus. In either of the prior arrangements, each sampling projectile is fired from a radial bore formed in the side of a solid steel gun body. The problem of providing for reliable and satisfactory stowage of the cable has been a troublesome one due largely to the bullet-like velocity with which the sampling projectile leaves the gun body thereby imposing very sudden and powerful strains on the cable as it uncoils from the storage space. According to one method heretofore proposed for stowing the cable, an annular recess is formed about the rear of the projectile and into which the cable is spirally coiled with the hope that the turns lying one on the other will remain in place as the gun is being handled and lowered into a borehole between the time of its assembly and its actual firing deep within the earth. In a second mode of stowage, the cable is coiled within an annular recess encircling the nose of the sampling projectile and one terminal is attached to the fore end of the projectile. In neither of these prior arrangements is there adequate assurance that the coiled cable will not become displaced during handling, and the likelihood of entanglement or serious damage to the cable as it is dispensed during firing is ever present and has come to be accepted as unavoidable. Attempts to provide retainers and guide devices for keeping the cable in place until the sampling projectile is fired and then acting to dispense the cable safely have not enjoyed success.

Exhaustive field tests have demonstrated that the arrangement constituting the present invention is highly superiorto prior constructions and obviates the many difliculties heretofore experienced. Essentially, the basic principle involves use of the cables inherent resiliency and slight stiffness to hold it frictionally engaged with the interior walls of the hollow sampling projectile such that it is positively retained in place therein with the cable axis aligned with the direction of its travel upon the firing of the projectile. In this manner is avoided the suddenly imposed change of direction on the cable inherent in prior designs and the passage of the cable across sharp edges of the projectile or the gun body as it is dispensed is entirely avoided.

Further important features of the invention include the special terminals or attachment means for the cable ends and the elimination of all sharp edges on both the gun body and the projectile wherever contact with the cable is possible. The elimination of the annular cable storage recesses at one or the other end of the projectile leaves in wireline 13 and having a series of leads 18 connected to insulated terminals and extending through a passage-.

to receiveand frictionally retain the retrieving cable for the projectile until the gun is fired.

Another object of the invention is the provision of a formation sampling apparatus wherein the retrieving cable is arranged for stowage with its axis aligned with and closely adjacent the trajectory axis of the projectile.

Still another object of the invention is the provision of a retrieving cable for a formation sampling apparatus having specially designed terminals permitting instant and free swiveling movement of the cable as necessary for thespeedy and accurate dispending thereof during firing of the core barrel. I

A further object is the provision of a core sampler device utilizing a plurality of retrieving cables arranged to be compactly stowed in side-by-side relation lengthwise of the" sampling projectile for rapiddispensing through the rear open end of the projectile.

Another object is the provision of a sampling projectile having simpler and more effective means for confining the explosive 'gases and making more efiicient use thereof during the firing of the gun.

Afurther object is the'provision of a sampler gun having an improved mode of retaining the sampling projectile in assembled position prior to firing.

These and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawings to which they relate.

Referring now to the drawings in which a preferred I embodiment of the invention is illustrated:

"Figure 1 is a side elevational view of a sampler gun projectiles after firing and another in readiness for firing:

Figure 3 is a transverse sectional view taken along line 3-3 on Figure 2;"

Figure 4 is an enlarged fragmentary view taken along line 4+4 of Figure 3;

And Figure 5 is a transverse sectional view taken along line 5-5 on Figure 3.

The present application is a continuation-in-part of my co-pending application for United States Letters Patent Serial No.'333,424, filed January 27, 1953, entitled Sidewall Sampler, now abandoned.

Referring to the drawings and particularly to Figures 1 and 2, it will be observed that the gun assembly designated generally 10 includes a cylindrical body 11 having a cablehead 12 connected to a wireline 13 of the, type having one or more. insulatedelectrical conductors embedded therein. The main portion of the gun body includes at least one group of firing stations 14for the formation sampler devices, a cutout or recess 15 therebelow in which the sampler devices are adapted to be suspended after firing, and the usual bull plug 16 at its lower end. The hollow cablehead 12 encloses a firing mechanism 17 connected with the conductors embedded way 19 in the gun body, each lead is connected to an igniter assembly 20 operable when energized to ignite and fire a propellent charge 21 associated with each of the 7 sampler projectiles.

The sampler devices, or projectiles form an important feature of the invention and are designated generally 25. Each makes a sliding fit within a shouldered bore 26 extending diametrically through. gun body 11, the bore having a large shoulder 27 intermediate its ends and a shallow shoulder 28 adjacent its rear end. The latter provides an abutment or stop for the rear end of the sampling projectile while shoulder 27 forms part of a chamber enclosing a ring 21 of a suitable exposive or other propellent material.

Sampling projectile 25 is preferably formed from a unitary piece of tubular, high-strength steel having a thick main wall and a radial enlargement 30 near its forward end provided with an annular groove 31. seating an annular elastomeric seal 32 such as the well-known O- ring type of shielding device. A similar annular groove 33 formed in the gun body slightly rearward of shoulder 27 seats an elastomeric O-ring 34. It will be noted that grooves 31' and 33 are located substantially equal distances inwardly from the opposite ends of bore 26 and cooperate with the sampling projectile to seal out well fluids and to retain the expanding gases of the propellent charge captive for a maximum period as the projectile is being propelled from the gun body thereby utilizing to a maximum the forces released by the firing of the propellent charge. 7

The interior wall 35 of the sampling projectile is of uniform diameter except at its forward endwhere it converges slightly in a smooth-surfaced frusto-conical section 36 terminating in a blunt-nosed cutting edge 37. The outer surface of this edge flares backwardly and outwardly to a merger with the periphery of flange 30. Due to the restriction provided by the converging section 36, it will be understood that the formation is permitted to expand gradually as it enters the sampling projectile and releases internal stresses imposed on the formation sample by subsurface pressure and weight conditions. Preferably the amount of expansion permitted is somewhat less than required for complete release of internal stresses thereby assuring that the sample will frictionally engage surface 35- until forcibly removed through the rear end of the sampling projectile.

The rear end of the sampling projectile is provided with a threaded recess 39 for seating a cable anchorage ring 40 which is releasably locked in. assembled position by a threaded bushing 41. To be noted in particular isthe outwardly flaring surface 42 at the outer end of the bushing providing a smooth bearing surface for the retrieving cables to be described presently.

Flexible connector means for holding the sampling projectile 2S captive after firing into the borehole wall and for retrieving them to the surface consists preferably of a pair of high-strength flexible cables4'5, 46. Desirably of the same length, these cables are provided at one end with ball terminals 47 adapted. to seat freely within retaining sockets 48 formed in the gun body at the rear end of bore 26. The cable attachments or anchorages so provided for the cables is shown in enlarged view in Figure 4 wherein the cable is shown as assembled to socket 48 by a retainer clip 49 and screws 50. It will be understood that each cable has such an anchorage, the sockets thereof being preferably located on the diametrically opposite sides of bore 26. Although the opposite ends of the cables are herein illustrated as swaged into enlarged portions 51 of the cable anchorage ring 40, it will be understood that these ends may be provided with ball terminals socketed in enlarged portions 51, if preferred.

The manner of stowing and retaining the cable interiorly of bores 35 in sampling projectiles 25 is em phasized. Preferably, cables 45 and 46 are wound from stranded high-strength wire having considerable resilience and being readily flexible. The resiliency and flexibility of the cables, together with the rough surfaceprovided by their stranded construction, gives them a high friction surface adapted to be held resiliently in contact with the interior surface of the sampling projectiles as is made clear by Figures 3 and 5. Although the cables may be coiled in various manners for insertion into the projectiles, a preferred manner of coiling is illustrated. This method of coiling provides an unusually long frictional contact between the cables and the interior wall of the projectiles thereby providing more than adequate assurance against dislodgment of the cables during handling of the gun both before and during lowering into a borehole. It will be observed that the cables extend parallel and closely adjacent the axis of the opening in the sampling projectile and that their terminal ends are likewise located close to this axis. This significance and importance of this relationship will be appreciated when it is borne in mind that the firing of propellent charge 21 results in the high velocity propulsion of the core barrel from the gun body into the adjacent formation. This high velocity projection of the projectile taken with the inertia of the cables accounts for the latter trailing behind the projectile and the expansion of the cable turns laterally into bore 26 without, however, becoming entangled or coming into contact with any sharp corners or without being required to change direction as the forward end of the cable follows the projectile. Contrary to the common experience with prior stowage arrangements for the cable, it is found that the use of the present invention never results in damage to the cable, nor is any difficulty experienced with the cable becoming displaced from its stowage position during handling of the gun.

Desirably, the sampling projectiles are held fully seated in bores 26 with their rear ends abutting shoulders 28 by retaining means designated generally 55 here shown as seating against the exterior surface of the sampling projectiles adjacent their forward ends. For example, such retaining means for the respective projectiles may comprise a pair of threaded plugs 56 seated in diametrically aligned bores opening through the interior surface of bore 26. Their pointed inner ends 57 seat firmly against the nose of the sampling projectiles and are adapted to be sheared oif by the force of the propellent charge 21 when fired. Consequently, plugs 56 must be replaced after each firing of the gun but this is an easily performed task for obvious reasons.

The mode of. use of the invention will be self-apparent from the foregoing description. Following lowering of the fully assembled gun to the desired level within a borehole, an electrical. circuit is closed by an operator at ground level sequentially energizing igniters 20 to ignite the propellent charges 21 one at a time, as desired. As a given charge is fired the associated sampling projectile is propelled from bore 26 at a velocity in the range of 1,000 feet per second, the actual velocity being augmented to a considerable extent by reason of the gastight seals maintained at the opposite ends of the core barrel until the moment of its exit from the bore by sealing gaskets 32, 34, as well as by the temporary restraining action of shear pins 57. The shear pins provide as surance of maximum propelling capability of the charge by detaining the projectile until high pressures have developed within the charge chamber. In the main, retrieving cables 45, 46 tend to follow the sampling projectile but at a slower velocity due to their high inertia and the fact that the charge does not act directly on them. The movement of the cables is in the same direction as the sampling projectile and axially of bore 26. The bluntedged nose of the sampling projectile blasts away a ring of the formation as a cylindrical sample enters bore 35, the entering end being allowed to expand gradually by flaring surface 36 to relieve internal stresses existing within the sample.

Following the firing of each of the several sampling projectiles mounted along the length of the gun assembly, the operator withdraws the gun causing retrieving cables 45,. 46 to tilt the projectiles and sever the captive samples from the rock formation opposite the nose end of the projectiles. Thereafter the captive samples are withdrawn as they hang suspended from the cables, the recesses 15 at the lower end of the gun assembly offering protection to the sampling projectiles 25 during withdrawal from the borehole. Once recovered, bushings 41 are detached to release ring 40 and allow the formation sample to be pushed from the rear end of the sampling projectile for examination and testing.

The gun assembly is restored to operation for recovering additional samples by reassembling the cables and bushings to the sampling projectiles and reinserting the same into the bores after the same have been fitted with new charges of propellent material and new igniters, the projectiles being locked in place by new shear plug units 56.

While the particular formation sampling apparatus herein shown and described in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiment of the invention and that no limitations are intended to the details of construction or design herein shown other than as defined in the appended claims.-

I claim:

1. A device for obtaining samples of formations traversed by earth boreholes comprising: a gun body adapted to be lowered into a borehole; a gun bore in said body; a tubular sampling projectile initially contained in said gun bore and having an axial passage therein open at the rear end thereof; propulsion means, including a combustible propellent, operatively associated with said gun bore and projectile for propelling said projectile axially from said gun bore into an adjacent formation wall; and at least one elongated, flexible connector member initially positioned and substantially wholly contained within said axial passage in said projectile and having one end thereof attached by a projectile-attachment means to said projectile adjacent the rear end thereof; and having the other end thereof extending out through the rear end opening of said axial passage and attached by a gun body attachment means to the gun body adjacent the rear end of said gun bore.

2. A device for obtaining samples of formations traversed by earth boreholes comprising: a gun body adapted to be lowered into a borehole; a gun bore in said body,

said gun bore having an inwardly-projecting, forwardlyfacing shoulder adjacent the rear end thereof; a tubular sampling projectile initially contained in said gun bore with a rear end portion thereof seated against said shoulder, said projectile having an axial passage therein open atthe rear end thereof; propulsion means including a combustible propellent, operatively associated with said gun bore and projectile for propelling said projectile axially from said gun bore into an adjacent formation wall; and at least one elongated, flexible connector means initially positioned and substantially wholly contained within said axial passage in said projectile and having one end thereof attached by a projectile-attachment means to said projectile adjacent the rear end thereof, and having the other end thereof extending out through the rear end opening of said axial passage and attached by a gun body attachment means to the gun body adjacent the rear end of said gun bore.

3. A device according to claim 1 in which the said gun body attachment means includes a ball terminal attached to said flexible connector means and seated with limited freedom for swiveling movement in a socket attached to said gun body adjacent the rear end of said gun bore.

4. A device according to claim 1 in which said projectile attachment means includes a counterbore in the rear end portion of said axial passage, forming a radiallyinwardly extending, rearwardly-facing annular shoulder;

an annular anchorage ring fitted in said counterbore adjacent said shoulder, said flexible connector means being attached to said anchorage ring; and a retainer bushing fixed in the rear end portion of said counterbore,

for retaining said anchorage ring in said counterbore.

5. A device according to claim 4 in which said retainer bushing is formed with a rounded outwardly-flared interior surface at its inner rearward end providing a smoothly curved inner bearing surface for said flexible connector means.

6. A device for obtaining samples of formations traversed by earth boreholes comprising: a tubular projectile adapted to be fired into an earth formation to obtain a sample thereof, said projectile having a rock-cutting forward end portion flaring outwardly and rearwardly, a shouldered counterbore at its rear end, an annular cable anchorage ring in said counterbore, and a retaining bushing locking said ring in said counterbore, said bushing having a wide, rounded, outwardly flared interior surface at its rearward end providing a smooth bearing surface for a retrieving cable attached to said ring.

7. Apparatus as defined in claim 6 including a retrieving cable secured at one end to said anchorage ring and having a ball terminal at the opposite end adapted to have free swiveling movement in an anchorage socket therefor.

8. Apparatus as defined in claim 6 wherein the forward rock-cutting end of said core barrel has an annular outwardly-opening groove, and an elastomeric sealing member seated in said groove.

9. Apparatus as defined in claim 6 wherein the said counterbore at the rear end of said projectile is threaded,

and said bushing holding said ring seated in said counterbore makes threaded engagement with the threads of said counterbore.

10. Apparatus as defined in claim 6 wherein the rear end of said projectile is provided with a cable anchorage ring, and a bushing threadedly connected to said rear end detachably holding said ring assembled to said projectile, said bushing and ring being removable to permit a formation sample to be discharged rearwardly from said barrel after the latters recovery from an earth borehole. 7

11. A device for obtaining samples of formations traversed by earth boreholes; comprising: a cylindrical gun body having a bore opening through its side wall and an abutment adjacent the rear end thereof providing a stop for a sampler projectile; a hollow sampler projectile adapted to fit slidingly through the outer end of said bore and to be propelled therefrom by a propellent charge housed within said gun body in communication with a radial wall portion of said projectile; and retainer means carried by said gun body with an inner edge thereof projecting inwardly through the wall of said bore adjacent the forward end of said projectile into engagement with the forward end portion of said projectile to hold the latter in a position within said bore with the rear end of said projectile seated against the said abutment, said retainer means being adapted to be sheared as'the projectile is propelled from said bore at high velocity following ignition of such propellent charge. A

12. Apparatus as defined in claim 11 wherein said retainer means comprises a shear pin provided with external threads engageable with seating threads formed in said gun body, the forward end of said shear pin having a small cross-section and extending into engagement with an exterior surface of said projectile in a manner to lock the same assembled within said gun bore.

13. Apparatus as defined in claim 12 provided with a plurality of said shear pins disposed diametrically opposite one another adjacent the forward end of said gun bore.

14. A device for obtaining samples of formations traversed by earth boreholes comprising: a gun body having a transverse bore opening through at least one side of said body; a formation-sampling projectile open at both ends and making a sliding fit within said bore; a chamber within said body for containing a propellent charge, said chamber being formed in part by said bore and in part by said projectile and providing an acting surface on said projectile for such charge for propelling said projectile from said bore; an elongated, flexible retrieving member initially housed, prior to propulsion of said projectile from said barrel, largely within said projectile, said retrieving member having one end thereof secured to said projectile and the other end thereof extending through the open rear end of said projectile and secured to the gun body adjacent the rear end of said gun bore.

15. A device for obtaining samples of formations traversed by earth boreholes comprising: a gun body having a transverse bore opening through at least one side of said body and having an abutment adjacent the rear end of said bore providing a stop for a sampling projectile; a formation-sampling projectile open at both ends and making a sliding fit Within said bore, said projectile initially being positioned within said bore with a rear end portion thereof seated against said abutment; a chamber within said body for containing a propellent charge, said chamber being formed in part by said bore and in part by said projectile and providing an acting surface on said projectile for such charge for propelling said projectile from said bore; an elongated, flexible retrieving member initially housed prior to propulsion of said projectile from said barrel, largely within said projectile, said retrieving member having one end thereof secured to said projectile and the other end thereof extending through the open rear end of said projectile and secured to the gun body adjacent the rear end of said gun bore.

16. A device for obtaining samples of formations traversed by earth boreholes comprising: a gun body having a transverse bore opening through at least one side of said body; a formation-sampling projectile open at both ends and making a sliding fit within said bore; a chamber within said body for containing a propellent charge, said chamber being formed in part by said bore and in part by said projectile and providing an acting surface on said projectile for such charge for propelling said projectile from said bore; an elongated, flexible retrieving member initially housed, prior to propulsion of said projectile from said barrel, largely within said projectile, said retrieving member having one end thereof secured to a rear end portion of said projectile and the other end thereof extending through the open rear end of said projectile and secured to the gun body rearwardly of the rear end of said projectile.

17. Apparatus as defined in claim 16 wherein said cable is coiled so that the planes of the coils lie parallel to the barrel axis and with the exterior surfaces of the turns pressed against the diametrically opposed interior sides of said opening in said projectile.

18. A device for obtaining samples of formations traversed by earth boreholes comprising: a gun body having a bore opening through the Wall thereof; a hollow, formation sampling projectile having a sliding fit within said bore and being cooperable with the interior of said bore to form a chamber for a charge of propellent material for propelling said projectile from said bore; an elongated retrieving cable connected between said body and said projectile for retrieving the latter after the firing of such charge; said body having an opening extending from the exterior of said body into said bore, and retainer means mounted in said opening and having an outer end accessible exteriorly of the body and an inner end extending inwardly beyond the interior side wall of said bore into contact with the forward end portion of said projectile to hold the same in assembled position, the inner end of said retainer means being adapted to be sheared by said projectile following the ignition of such charge and the creation of gas pressures within said charge chamber in excess of a predetermined value.

References Cited in the file of this patent UNITED STATES PATENTS 2,391,869 Bandy Jan. 1, 1946 2,408,419 Foster Oct. 1, 1946 2,511,408 Lebourg June 13, 1950 THER REFERENCES Ser. No. 271.524, Schlumberger (A. P. C.), published May 25, 1943. 

